Protocols for remote vehicle access systems

ABSTRACT

A wireless communications system for an automotive vehicle includes a vehicle control unit and a fob. The vehicle control unit includes a vehicle transceiver. The fob includes a fob transceiver and a fob control unit and is configured to transmit and receive communications through at least two channels. The fob control unit is programmed to transmit a preamble through the first of the at least two channels, transmit a preamble through the second of the at least two channels during a null space following the preamble transmitted through the first channel, transmit a data packet payload through the first channel when a null space following the preamble in the second channel is detected, and transmit a data packet payload through the second channel when a null space following the preamble in the second channel is detected. Communications are interleaved between the first and second channels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the divisional application of U.S. application Ser.No. 15/039,124, filed May 25, 2016, which is the national phase ofInternational Application No. PCT/US2014/068155, filed Dec. 2, 2014,which claims the benefit of U.S. Provisional Patent Application No.61/911,216, filed Dec. 3, 2013, which are hereby incorporated byreference in their entireties.

BACKGROUND OF THE INVENTION

In recent years, wireless communications have become increasinglyimportant in a number of vehicle control systems. Remote vehicle entrytransmitters/receivers, for example, are used for locking and unlockinga vehicle door, unlatching a trunk latch, or activating or deactivatingan alarm system equipped on the vehicle. This remote entry device iscommonly referred to a remote keyless entry (RKE) fob. The RKE fob istypically a small rectangular or oval plastic housing with a pluralityof depressible buttons for activating each one of the wirelessoperations. The RKE fob is carried with the operator of a vehicle andcan wirelessly perform these functions when within a predeterminedreception range of the vehicle. The RKE fob communicates with anelectronic control module within the vehicle via a RF communicationsignal.

Other communication modules may be provided within the vehicle system.These can include, for example, a tire pressure monitoring (TPM) system.A TPM system disposes pressure sensors on or within vehicle tires tosense the pressure within a respective tire and report low or highpressure conditions to a driver. TPM systems sense tire pressure withina tire and transmit a signal to a body-mounted receiving unit locatedexternal to the tire for processing tire pressure data. Interference mayoccur when the signal transmitted by the transmitting devices of TPMsystem is broadcast in the same operating frequency of the RKE receiver.

Even more recently, complex embedded electronic systems have becomecommon to provide access and start functions, and to provide wideranging functions to improve driver safety and convenience. Thesesystems include Passive Entry and Passive Start (PEPS) systems. In PEPSsystems, a remote receiver and transmitter (or transceiver) is carriedwith the user in a portable communication device such as a key fob or acard. The portable communication device when successfully challengedtransmits a radio frequency (RF) signal to a module within the vehiclefor performing a variety of remote vehicle function such doorlock/unlock, enabling engine start, or activating external/internallighting. Passive entry systems include a transmitter and receiver (ortransceiver) in an electronic control module disposed within thevehicle. The transceiver is typically in communication with one or moredevices (e.g., door lock mechanism) for determining when a request foractuation of a device is initiated (e.g., lifting a door handle) by auser.

Upon sensing the request for actuation, the transceiver broadcasts apassive entry interrogating signal. The fob upon receiving theinterrogating signal from the ECU, the portable communication devicedetermines if the interrogating signal is valid. If it is determined avalid signal, then the fob automatically broadcasts an output signalwhich includes an encrypted or rolling identification code to theelectronic control module. The electronic module thereafter determinesthe validity of the output signal and generates a signal to the deviceto perform an operation (e.g., the door lock mechanism to unlock thedoor) if the output signal is determined valid.

As the number of wireless communication systems and number of wirelesscontrols has increased, it has become increasingly important to assurethat communications are fast and efficient. Thus, there exists a needfor improved communications systems that can quickly transmit andprocess wireless communications packets.

SUMMARY OF THE INVENTION

The present disclosure provides a number of wireless protocols fordecreasing latency, increasing redundancy, and increasing immunity tointerference in transmissions within a vehicle, or between a vehicle anda fob or other personal communication device or token.

In one aspect, the present disclosure describes a wirelesscommunications system for an automotive vehicle comprising a controlunit in the automotive vehicle including a transceiver configured toreceive signals from a fob, and a fob comprising a transceiver and acontrol unit, where the fob configured to transmit a wake-up signal tothe control unit in the automotive vehicle. A data packet providingcommands for commanding the control unit to perform a vehicle functionis embedded within the wake-up packet. The data packet can comprise anapplication code.

In another aspect, a wireless communications system for an automotivevehicle is disclosed comprising a control unit in the automotive vehicleincluding a transceiver adapted to transmit and receive serialcommunications in at least two channels, and a fob comprising atransceiver and a control unit, the fob configured to transmit andreceive communications through the at least two channels. The controlunit in the fob is programmed to transmit a preamble through the firstof the at least two channels and to transmit a preamble through thesecond of the at least two channels during a null space following thepreamble transmitted through the first channel. The control unit isfurther programmed to transmit a data packet payload through the firstchannel when a null space following the preamble in the second channelis detected, and to transmit a data packet payload through the secondchannel when a null space following the preamble in the second channelis detected. Communications between the first and second channels aretherefore interweaved. The transmission of the payload data packets ineach of the first and second channels are spaced variably to improvenoise immunity.

In yet another aspect, a wireless communications system for anautomotive vehicle is disclosed comprising a control unit in theautomotive vehicle including a parallel processing transceiver adaptedto transmit and receive communications in a plurality of channels andcorresponding sub-channels, and a fob comprising a parallel processingtransceiver adapted to transmit and receive communications in aplurality of channels and corresponding sub-channels and a control unit.The fob is configured to transmit and receive communications through theparallel processing channels, and the control unit in the fob isprogrammed to transmit data packets corresponding to a vehicle functionselected by each of a plurality of fobs through corresponding subchannels in a first channel, and transmit the data packets correspondingto each of the plurality of fobs through corresponding sub channels in asecond channel.

In still another aspect, a wireless communications system for anautomotive vehicle comprises a control unit in the automotive vehicleincluding a parallel processing transceiver adapted to transmit andreceive communications in a plurality of channels and correspondingsub-channels, and a fob comprising a parallel processing transceiveradapted to transmit and receive communications in a plurality ofchannels and corresponding sub-channels and a control unit. The fob isconfigured to transmit and receive communications through the parallelprocessing channels, wherein the control unit in the fob is programmedto transmit data packets corresponding to a vehicle function for each ofa plurality of fobs through corresponding sub channels in a firstchannel, and transmit the data packets corresponding throughcorresponding sub channels in a second channel.

These and other aspects of the invention will become apparent from thefollowing description. In the description, reference is made to theaccompanying drawings which form a part hereof, and in which there isshown a preferred embodiment of the invention. Such embodiment does notnecessarily represent the full scope of the invention and reference ismade therefore, to the claims herein for interpreting the scope of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless vehicle communication system including avehicle, vehicle transceiver module, and an antenna communicating with amobile electronic user device.

FIG. 2 is a block diagram of an exemplary vehicle transceiver modulethat can be used in accordance with the disclosed system.

FIG. 3 is a block diagram of an exemplary key fob that can be used inaccordance with the disclosed system.

FIG. 4 is a simplified bottom view of a vehicle having four tires andcorresponding tire condition monitors.

FIG. 5 is a block diagram of a tire condition monitor.

FIG. 6, illustrates a typical radiofrequency communications protocolbetween a key fob, tire condition sensor or other vehicle system incommunication with the vehicle transceiver.

FIG. 7 illustrates a protocol including a data packet for performing afunction such as opening a door that is embedded in the wakeup package.

FIG. 8 is an alternate embodiment of the protocol of FIG. 7, in which anapplication code is embedded in a wakeup signal and multiple functionsare to be performed.

FIG. 9 illustrates a typical prior art two-channel protocol architectureused in wireless communications between a vehicle transceiver and a keyfob or other wireless communications device.

FIG. 10 illustrates an interweave protocol.

FIG. 11 illustrates an alternative interweave protocol.

FIG. 12 illustrates a typical prior art series data process.

FIG. 13 illustrates a first embodiment of a parallel wirelesscommunications.

FIG. 14 illustrates a second embodiment of a parallel wirelesscommunications.

FIG. 15 illustrates a third embodiment of a parallel wirelesscommunications.

FIG. 16 illustrates a fourth embodiment of a parallel wirelesscommunications.

FIG. 17 illustrates an alternate embodiment of a vehicle transceiver.

FIG. 18 illustrates an alternate embodiment of a key fob 200corresponding to the vehicle transceiver of FIG. 17.

FIG. 19 illustrates a vehicle and corresponding zones of detection.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a wireless vehicle communication system 100 isshown. The system 100 comprises a vehicle 102 including a vehicletransceiver module 110 having an antenna 104 communicating with a mobileelectronic user device 200, which here is shown and described as a keyfob. It will be apparent that the mobile electronic user device 200 canbe many types of application-specific or personal computerized devices,including, for examples, transponder cards, personal digital assistants,tablets, cellular phones, and smart phones. Communications are typicallydescribed below as bi-directional between the vehicle transceiver moduleand the key fob 200 and other devices, although it will be apparent thatin many applications one way communications will be sufficient.

The key fob 200 can include one or more user input device 202 and one ormore user output or alert devices 204. The user input devices 202 aretypically switches such as buttons that are depressed by the user. Theuser output alert devices 204 can be one or more visual alert, such aslight emitting diodes (LEDs), a liquid crystal display (LCD), andaudible alarm, or a tactile or vibratory device. A single function canbe assigned to each input device 202 or user alert devices 204, or acombination of input devices or a display menu could be used to requesta plethora of functions via input device sequences or combinations. Keyfobs can, for example, provide commands to start the vehicle, providepassive entry (i.e., automatic unlocking of the doors of the vehicle 102when key fob 200 is within a predetermined proximate distance of thevehicle 102), activate external and internal vehicle lighting,preparation of the vehicle locking system, activation of a vehiclecamera for vehicle action in response to camera-detected events, openingwindows, activating internal electric devices, such as radios,telephones, and other devices, and adjustment of driver preferences(e.g., the position of the driver's seat and the tilt of the steeringwheel) in response to recognition of the key fob 200. These functionscan be activated input devices 202 or automatically by the vehicle 102detecting the key fob 200. Although a single key fob is shown here, itwill be apparent that any number of key fobs could be in communicationwith the vehicle transceiver module, and the vehicle transceiver module110 and corresponding control system could associate a different set ofparameters with each key fob.

In addition, the vehicle transceiver module 110 can activate output oralert devices 204 to notify the vehicle user that the key fob 200 iswithin communication distance or some other predetermined distance ofthe vehicle 102; notify the vehicle user that a vehicle event hasoccurred (e.g., activation of the vehicle security system), confirm thatan instruction has been received from the key fobs 200, or that anaction initiated by key fob 200 has been completed.

Referring now to FIG. 2, a block diagram of an exemplary vehicletransceiver module 110 that can be used in accordance with the disclosedsystem is illustrated. The vehicle transceiver module 110 includes aprocessor or controller 112, memory 114, a power supply 118, andtransceiver circuitry 116 communicating through the antenna 104.

The transceiver circuitry 116 includes receiver circuitry 122 andtransmitter circuitry 120 for bi-directional communications. Thereceiver circuitry 122 demodulates and decodes received RF signals fromthe key fob 200, while the transmitter provides RF codes to the key fob200, as described below. Although separate transmitters and receiversare shown, one or more transceivers could also be used.

The memory 114 stores data and operational information for use by theprocessor 112 to perform the functions of the vehicle transceiver module110, and to provide the vehicle function(s) described above. Thecontroller 112 is also coupled to a higher level vehicle controller orcontrollers (not shown), which can include, for example, a vehicle bussuch as a Controller Area Network (CAN) bus system and correspondingvehicle control system, and can both receive command signals from thevehicle control system and provide command signals and other informationto the vehicle control system. Information available to other devicesfrom the CAN bus or other online vehicle bus may include, for example,vehicle status information regarding vehicle systems, such as ignitionstatus, odometer status (distance traveled reading), wheel rotation data(e.g., extent of wheel rotation), etc. Vehicle status data can alsoinclude status of electronic control systems including among others,Supplemental Restraint Systems (SRS), Antilock Braking Systems (ABS),Traction Control Systems (TCS), Global Positioning Systems (GPS),Environmental monitoring and control Systems, Engine Control Systems,cellular, Personal Communications System (PCS), and satellite basedcommunication systems and many others not specifically mentioned here.

The transceiver 110 is coupled to the antenna 104 for receiving radiofrequency (RF) signals from the key fob 200 and transmitting signals tothe key fob 200. Although the antenna 104 is shown as being external tothe vehicle transceiver module 110 and on the exterior of the vehicle102, the antenna 104 may also be implemented within the confines of thevehicle 120 or even within the vehicle transceiver module. A number ofantennas can be embedded, for example, in the headliner of a vehicle, orelsewhere within a vehicle. Although a bi-directional transceiver 110 isshown, it will be apparent that one way communications from the key fob200 to the vehicle 102, or from the vehicle to the key fob 200 can alsobe provided, and that both a transmitter and receiver would not berequired.

Referring now to FIG. 3, a block diagram of an exemplary key fob 200that can be used in accordance with the disclosed system includes acontroller 206, memory 208, transceiver 210 and corresponding antenna212, and a power supply 214 (such as a battery). User input devices 202and user alert devices 204 are in communication with the controller 206.The transceiver circuitry 210 includes receiver circuitry andtransmitter circuitry, the receiver circuitry demodulating and decodingreceived RF signals to derive information and to provide the informationto the controller or processor 206 to provide functions requested fromthe key fob 200. The transmitter circuitry encodes and modulatinginformation from the processor 206 into RF signals for transmission viathe antenna 212 to the vehicle transceiver 110.

Although many different types of communications systems could be used,conventional vehicles typically utilize four short-range RF basedpeer-to-peer wireless systems, including Remote Keyless Entry (RKE),Passive Keyless Entry (PKE), Immobilizer and Tire Pressure MonitoringSystem (TPMS). RKE and TPMS typically use the same high frequency withdifferent signal modulation (315 MHz for US/NA, 433.32 MHz for Japan and868 MHz for Europe), whereas the PKE system often requires abidirectional communication at a low frequency (125 KHz) between the keyfob and the receiver module and a unidirectional high frequencycommunication from key fob to the receiver module. The Immobilizersystem also typically uses a low frequency bidirectional communicationbetween the key fob and the receiver module. Receivers for these systemsare often standalone and/or reside in various control modules like BodyControl Module (BCM) or Smart Junction Block (SJB). By using differentradios with different carrier frequencies and/or modulation schemes,collisions between transmissions from separate wireless communicationsystems in the vehicles can be avoided.

The antenna 212 located within the fob 200 may be configured to transmitlong-range ultra-high frequency (UHF) signals to the antenna 104 of thevehicle 100 and receive short-range Low Frequency (LF) signals from theantenna 104. However, separate antennas may also be included within thefob 200 to transmit the UHF signal and receive the LF signal. Inaddition, antenna 104 and other antennas in the vehicle may beconfigured to transmit LF signals to the fob 200 and receive UHF signalsfrom the antenna 212 of the fob 200. Also, separate antennas may beincluded within the vehicle 102 to transmit LF signals to the fob 200and receive the UHF signal from the fob 2200

The fob 200 may also be configured so that the fob controller 206 may becapable of switching between one or more UHF channels. As such, the fobcontroller 206 may be capable of transmitting a response signal acrossmultiple UHF channels. By transmitting the response signal acrossmultiple UHF channels, the fob controller 206 may ensure accuratecommunication between the fob 200 and the vehicle transceiver 110.

Referring still to FIG. 3, a motion detection device, such as a movementsensor 216, can optionally be included in the key fob 200 to detectmovement of the key fob 200. The controller 206 can, for example,utilize the motion or lack of motion detected signal from the movementsensor 216 to place the key fob 200 in a sleep mode when no motion isdetected for a predetermined time period. The predetermined time periodduring which no motion is detected that could trigger the sleep modecould be a predetermined period of time or a software configurablevalue. Although the motion detection device is here shown as part of thekey fob, a motion detection device could additionally or alternativelybe provided in the vehicle 102.

The vehicle transceiver 110 may transmit one or more signals without anoperator activating a switch or pushbutton on the fob key 200, includinga wakeup signal intended to activate a corresponding fob 200. The fob200 may receive signals from the transceiver 110 and determine thestrength or intensity of the signals (Received Signal StrengthIndication (RSSI)), which can be used to determine a location of the fob200.

Referring now to FIG. 4, an exemplary vehicle 102 typically includes 4tires 122, 124, 126, and 128 and an associated tire condition monitor302, 304, 306, and 308, respectively, for sensing a condition of thetire. The tire condition may be, for example, the gas pressure withinthe tire, the temperature of tire, both the pressure and temperature, orother tire condition. Referring now also to FIG. 5, by way of example, atire condition monitor 302 is illustrated schematically and isrepresentative of each of the other tire condition monitors 304, 306,and 308. As shown in FIG. 5, each tire condition monitor 302, 304, 306and 38 includes a sensor 310 for sensing the gas pressure or temperaturein the associated tire. The tire condition monitor 302 may also includeadditional sensors to sense other tire parameters.

Tire condition monitor 302 also includes a transmitter 312 incommunication with the sensor 310. Transmitter 312 is coupled to anantenna 314 to transmit signals that are indicative of the tirecondition sensed by the sensor 310. The tire pressure monitor 302further includes a power supply, such as battery 318, which providespower to at least the transmitter 312. The tire pressure signals mayinclude information or a signal or a message packet portionrepresentative of the status of the battery 318, including a low batterystatus. The tire condition signals are transmitted to the vehicletransceiver 110, and are preferably radio frequency (“RF”) signals ofthe type discussed above, although other signal types known in the artcould be employed. The tire pressure signals may be modulated in anyfashion known in the art, such as by Amplitude Shift Keying (“ASK”) orFrequency Shift Keying (“FSK”). transmitted together or separately. Thetire pressure signals 34 may also include information regarding othertire parameters, such as temperature.

Wakeup

Referring now to FIG. 6, in typical systems, RF communications betweenthe key fob 200, tire condition sensor 302, 304, 306, 308 or othervehicle system in communication with the vehicle transceiver 110 beginswith a wakeup signal 400, followed by a space 402, and then a payload404. Upon receipt of a wakeup signal 400, the vehicle transceiver 110may or may not transmit a response signal. The vehicle controller 112may also begin an authentication/response challenge sequence between thevehicle controller 112 and the fob 200. Typical wake up packets areredundant tones with no additional information. This typicalarchitecture therefore leads latency because the wake up packet must bereceived and verified before the functionality of the data packet can bedetermined. There can be a significant delay between requesting afunction (open doors, activate lights, receive a tire condition update,etc.), and the performance of the function. Because of the increasedresponse times, these delays can be particularly undesirable in vehiclesthat include multiple systems with multiple wireless functions.

Referring now to FIGS. 7 and 8, embodiments of the present inventionembed a payload package providing data or application code necessary toperform a function within the wake up packet. The embedded data packetsprovide a number of advantages. By providing additional information inthe wake up packet, the data packet can be received by the vehiclecontroller 112 earlier in the transmission, and can also be receivedrepeatedly early in the process. The vehicle controller therefore candetermine the function and perform the function more quickly. Processingwill occur at an earlier time reducing the overall latency. Furthermore,if multiple vehicle functions use similar wake up packets, applicationcode may be embedded with or without a payload data packer to identifythe payload data that is to be processed.

Referring first to FIG. 7, in one embodiment, a data packet forperforming a single function such as opening a door can be embedded inthe wakeup package 406. Wakeup packet 406 is followed by a nulltransmission 402. Subsequently, a second payload package 404 istransmitted. Additional payload packets 405 and 407 follow. The vehicletransceiver 110 therefore receives a functional data packet commandinitially in the wakeup packet, reducing latency, and quickly receives asecond data packet, providing a redundant transmission that assuresappropriate activation quickly.

Referring now to FIG. 8, in an alternate embodiment, an application codecan be embedded in the wakeup signal 408 where multiple functions are tobe performed. For example, an application code can be used to provide asignal to personalize a vehicle for a user. Here, for example, thesignal can indicate a seat, steering wheel, and mirror adjustment to apredetermined setting for the identified user. Each of the followingpayload packages 404, 405, 407, can provide the data for the seatlocation, steering wheel adjustment, and mirror adjustment,respectively. In an alternate embodiment where multiple vehiclefunctions us similar wakeup packets, an application code is embeddedwithin the wake up packet to identify different functional payload datato follow. Thus, for example, the application code can indicate that thefirst payload 404 is a door opening data packet, while the second 405contains vehicle monitoring data, such as a TPM packet.

Interweave Techniques

Referring now to FIG. 9, a typical two-channel protocol architectureused in wireless communications between a vehicle transceiver 110 and akey fob 200 or other wireless communications device is shown. Here,wireless transmission of one channel or spectrum 410 is followed bywireless transmission of a second channel or spectrum 412, resulting infrequency-time voids or spectrum holes.

Referring now to FIG. 10, a first interweave protocol is shown. Here, atransmission is initially begun in a first channel 410. Thistransmission begins with a preamble 414, followed by a null space 415where no transmission occurs, which is then followed by a payload 420transmitting a data packet or application code. A second transmissionbegins on a second channel 412 when the preamble of the firsttransmission ends at time 416, the second channel 412 sending a preambletransmission 418 during the null space 415 in the transmission ofchannel 1. The first payload packet 420 transmitted in the first channel410 is transmitted during the null space 419 following the preamble 418in the second channel 412. Subsequent payloads from the first and secondchannels are transmitted during null periods in the opposite channel,resulting in an improved use of bandwidth. This technique maximizes useof the spectrum, and also reduces latency in the system by providing thesecond telegrammed packet to be transmitted at an earlier time slot.This reduced latency can be applied to a single function or multiplefunctions.

Referring now to FIG. 11, a second embodiment of an interweave protocolis shown. Here, as described above with reference to FIG. 10, thepreamble 418 sent through the second channel 412 occurs during a null415 in the first channel 410. Here, the timing of transmission of thepayloads 420, 424, and 428 in the first channel 410 occur during nullspaces in the second channel 412. Similarly, payloads 422, 426, and 430transmitted through the second channel 412 occur during null spaces inthe first channel 410. Here, the transmission times of the payloads arevaried during the null space such that payloads are randomlyinterspersed. Additionally, the timing of the transmissions during thenull regions can be randomized to help increase noise immunity. Forexample, when two vehicles operating on the same frequency are near oradjacent one another, the transmissions can interfere. The randomizedtransmission can help to avoid interference, and preventing jammingbetween adjacent or closely-spaced vehicles.

Parallel Processing

Referring now to FIG. 12, prior art wireless processing of data istypically performed in series, Here, a channel is assigned to eachwireless access (e.g. a key fob or other personal communicator) ordiagnostic device (a tire condition sensor, vehicle status sensor, orindividual module status sensor), and to each function associated witheach channel. Therefore, for example, a key fob 200 (FIG. 1) having afirst actuator 202 a for locking doors and a second actuator 202 b forunlocking doors will communicate serially over two separate channels.The first channel will be used to communicate instructions to lock thedoors, and the second channel to unlock the doors.

Referring again to FIG. 2, to provide parallel processing of data, thetransceiver circuitry 210 in the fob 200 and the transceiver circuitry120/122 in the vehicle control system 110 can be provided by a NCK2983from NXP corporation located in Nijmegen, Netherlands. Referring firstto FIG. 13, one method for providing parallel processing is shown. Hereeach communication channel 500, 500 a . . . 500 n is divided intosub-channels of data each corresponding to a key fob 200, 200 a . . .200 n expected to provide command data to the vehicle 102. As a result,communications can be processed in parallel, reducing time lags in datacommunications.

Referring now to FIG. 14, in an alternate embodiment, each channel 500,500 a . . . 500 n is divided into sub-channels of data based on commandfunctions expected to be received from a fob 200 or other vehiclecontrol system. Thus, for example, in the first transmission, a selectedfunction, e.g. the “door open” function is transmitted to each channel,starting with channel 500. Subsequently, the same information istransmitted to each channel, starting with channel 500 a. Data istherefore transmitted redundantly and on different sub-channels,increasing the speed and integrity of the transmission.

Referring now to FIG. 15, in another embodiment using parallelprocessing, commands for a single function 502, 502 a . . . 502 n areprovided repetitively in a number of sub-channels corresponding to aselected channel 500, 500 a . . . 500 n. This embodiment is particularlyuseful in situations where vehicles are adjacent other vehicles that maybe transmitting in the same frequency ranges.

Referring now to FIG. 16, in another embodiment using parallelprocessing, a full data packet 522 at high data rate is embedded withinthe “on” time boundary 520 of a single bit transmitted at a much slowerdata rate. Embedding a full data packet 522 reduces latency in thecommunications system by providing additional telegrammed packets to betransmitted at an earlier time slot. The full data packet 522 cantransmit a single function or multiple functions. If multiple functionsare to be carried out, application code can be used with or without theadditional payloads to provide information to the system regarding howto process the incoming data. The additional payloads decrease latency,and offer informational redundancy, therefore increasing the likelihoodthat the message will be processed correctly and quickly.

Motion Detection

Referring now to FIGS. 17 and 18 an alternate embodiment of a vehicletransceiver 110 and corresponding key fob 200 is shown, with likenumerals indicating like elements of those shown in FIGS. 2 and 3. Here,the vehicle transceiver 110 includes a motion detector 123 that is incommunication with the controller 112. The motion detector 123 senses anapproaching individual using Doppler, ultrasonic detection, or othermotion sensing devices. When motion is detected, the vehicle transceiver110 begins transmitting a LF polling signal to determine whether a fob200 is in the area. The receiver 210 in the key fob is either retainedin an “on” position, or is programmed to poll to receive the LF commandtransmitted from the controller 112, and to respond wirelessly in a highfrequency MHz, GHz range. When the vehicle transceiver 110 detects thefob, it determines which zone (A, B, C, D, E, F, FIG. 19) the fob 200 isin.

Although specific embodiments are described above, it will be apparentto those of ordinary skill that a number of variations can be madewithin the scope of the disclosure For example, although bidirectionalcommunications between the vehicle and remote control, passive entry,and sensor devices is shown and described, one-way communications canalso be used. It should be understood, therefore, that the methods andapparatuses described above are only exemplary and do not limit thescope of the invention, and that various modifications could be made bythose skilled in the art that would fall within the scope of theinvention. To apprise the public of the scope of this invention, thefollowing claims are made:

What is claimed is:
 1. A wireless communications system for anautomotive vehicle comprising: a vehicle control unit in the automotivevehicle including a vehicle transceiver adapted to transmit and receiveserial communications in at least two channels; and a fob comprising afob transceiver and a fob control unit, the fob configured to transmitand receive communications through the at least two channels, andwherein the fob control unit is programmed to: transmit a preamblethrough a first channel of the at least two channels; transmit apreamble through a second channel of the at least two channels during anull space following the preamble transmitted through the first channel;transmit a data packet payload through the first channel when a nullspace following the preamble in the second channel is detected; andtransmit a data packet payload through the second channel when a nullspace following the preamble in the second channel is detected, whereincommunications are interleaved between the first and second channels. 2.The wireless communications system of claim 1, wherein the transmissionof the data packet payloads in each of the first and second channels arespaced variably to improve noise immunity.
 3. The wirelesscommunications system of claim 1, wherein the fob control unit isprogrammed to randomly intersperse the data packet payload transmittedthrough the first channel and the data packet payload transmittedthrough the second channel over a transmission time.
 4. The wirelesscommunications system of claim 1, wherein the fob control unit isprogrammed to randomize a timing of (i) the transmission of the datapacket payload through the first channel when the null space followingthe preamble in the second channel is detected and (ii) the transmissionof the data packet payload through the second channel when the nullspace following the preamble in the second channel is detected.
 5. Thewireless communications system of claim 1, wherein the fob control unitis programmed such that the transmission of the data packet payloadthrough the first channel overlaps the null space following the preamblein the second channel.
 6. The wireless communications system of claim 5,wherein the fob control unit is programmed such that the null spacefollowing the preamble in the second channel overlaps a null spacefollowing the data packet payload through the first channel.
 7. Thewireless communications system of claim 6, wherein the fob control unitis programmed such that the transmission of the data packet payloadthrough the second channel overlaps the null space following the datapacket payload through the first channel.
 8. A method of wirelesslycommunicating between a fob and an automotive vehicle including atransceiver adapted to transmit and receive serial communications in afirst channel and a second channel, the method comprising: transmittinga first preamble through the first channel; transmitting a secondpreamble through the second channel during a first null space followingthe first preamble in the first channel; transmitting a first datapacket payload through the first channel when a second null spacefollowing the second preamble in the second channel is detected; andtransmitting a second data packet payload through the second channelfollowing the second null space in the second channel, whereincommunications are interleaved between the first and second channels. 9.The method of claim 8, wherein the transmission of the first and seconddata packet payloads in each of the first and second channels are spacedvariably to improve noise immunity.
 10. The method of claim 8, whereinthe first and second data packet payloads transmitted through the firstand second channels, respectively, are randomly interspersed over atransmission time.
 11. The method of claim 8, wherein a timing of thetransmission of the first data packet payload through the first channeland a timing of the transmission of the second data packet payloadthrough the second channel is randomized.
 12. The method of claim 8,wherein the first data packet payload is transmitted through the firstchannel during the second null space in the second channel.
 13. Themethod of claim 12, wherein the second data packet payload istransmitted through the second channel during a third null spacefollowing transmission of the first data packet payload through thefirst channel.
 14. The method of claim 13, wherein the second null spacefollowing the second preamble in the second channel overlaps the thirdnull space following the first data packet payload through the firstchannel.